The major goal of this proposal is the understanding in molecular terms of the coupling of membrane functions to metabolic energy, with an emphasis on active transport and oxidative phosphorylation. The hypothesis on which the proposal is based is that the coupling of oxidative energy to phosphorylation and active transport is the result of the electrochemical gradient of protons produced by the electron transport chain. Likewise, hydrolysis of ATP via the Mg2 ion-ATPase produces a protonmotive force which can energize other membrane functions such as transport. The transduction of energy from one membrane system to another will be studied through the biochemical isolation of the individual components of each system and followed by incorporation into artificial phospholipid vesicles. In that way in vitro analogs of biological membranes can be constructed, allowing a study of the function and mechanism of each system in isolation and in concert. The organization of proteins within biological membranes will also be studied in order to gain insight into the relationship of their localization within the membrane to their functions.